Tuesday, September 11, 2012

1975 Stratocaster Upgrades - Cruel Summer

Hot summer streets And the pavements are burning, I sit around

It has been another hot summer in my part of North Carolina, and I had to put things aside until the fall weather made it here.  A long to-do list added to the delay of work at the This Old Guitar workbench.  To help fill the gap, I've enlisted my old high-school pal / fellow guitar enthusiast /fellow engineer bj to be a guest blogger.  I hope you enjoy this posting that originally appeared on the Fender Forums:
This posting will chronicle the steps to swap my bridge pickup and a few other parts. I’m working with a mostly-stock 1975 Strat. Aside from being on the rotating pickup plan, I’ve rewired the selector switch to have the second tone control work the bridge and middle pickups. None of the changes I’m doing are innovative or otherwise special…I’m just gathering together a lot of information I’ve learned from this forum and other sources in one place, and hopefully clearly documented in case anyone is inspired to try it for themselves.

Our subject:

I’m replacing the current Seymour Duncan SSL-3, which replaced a DiMarzio SDS-1, which replaced the original. I’ve determined a SD SSL-6T is my pickup of choice. It is a good option for a basic vintage-ish sound to work with the originals, and a bit more punch when needed at the flip of a switch. The tapped/full output will be selected using a push/push switch on the bottom of a new tone pot.

For reference, I measured the DC resistance of the two original pickups and the two outputs of the new one, and the others I have:

Stock Neck: 5.82K
Stock Middle: 5.90K
SSL-6T Tapped: 6.75K
SSL-6T Full: 13.16K
SSL-3: 16.17K
SDS-1: 9.55K

So, going by resistance alone (Danger!)…the tapped output is a good fit with the originals. Also, the full output should have some kick to it, but nothing like the SSL-3. Aside from the curiosity factor, it is a good way to make sure there aren’t any wiring problems with the pickup before it is installed.

By the way, the SSL-6T is not an easy pickup to buy. Not impossible, just not stocked by any of the handful of places I checked. A special shout-out is made to Drew Bowman at Pro Audio Land for not only ordering it without any extra fee or hassle…but also for expediting the delivery to me when things got mis-routed arriving to him. So…if you shop online…consider PAL, just ‘cause they were nice to me :)

Here’s our new pickup:

In the process, I am also replacing the (well-worn) original 3-way switch with a new CRL 5-way. It is no longer possible to find and hold the ‘2’ & ‘4’ positions with any dependency, and certainly not in the middle of a song. Here, I narrowly succumbed to a bit of scope creep. During a moment of weakness, I thought of switching around which tone controls worked which pickups and and adding a second tone cap. Fortunately, I recovered and I’m sticking with the original plan of just changing the pickup…and replacing the tone cap with an Orange Drop of the same value…I can always mess with the wiring and other cap values later.

New Switches:

When it is all done, the completed wiring should look like this drawing:

Enough planning…let’s get started…

It is easier to remove the knobs while the pickguard is still attached to the body. Use two heavy picks, a slotted piece of leather, or two credit cards; but nothing metal. Work carefully and slowly until it comes loose. After removing the strings, move to the underside of the pickguard to start the disassembly. I like to keep a small bowl nearby to collect screws and other small parts. Put a towel between the pickguard and the body to avoid scratching the finish.

Before starting any disassembly, be sure you know where things are, and where they need to go…make notes, use little pieces of tape, take pictures…
Carefully unsolder the bridge pickup wires and pull them out of the way.
Carefully unsolder the wire connecting the second tone control to the cap on the first – it is usually the capacitor lead, so it might be easier to clip it…depending on your tools and skills. Unsolder the cap. Then remove the wires from the selector switch.

Carefully turn the pickguard over again and remove the tone pot, selector switch, and existing bridge pickup. Place them in a box for safe keeping.

Now...it looks like this:

Install the new pickup, switch, and pot, note location/orientation of lugs, etc. Adjust nuts on pot to set knob height to be even with the others.

So far, it looks like this:

Cut pickup wires to size, and twist/dress as needed to make it all fit well and look nice…unless you have a ‘swimming pool’ route, there isn’t a lot of space.

Solder the SSL-6T tapped- and full-output wires to the top and bottom lugs of one side of the switch. Cut and attach a wire from the center lug and add to ground bundle. Note: Duncan pickups are wound backwards from Fenders. The ‘ground’ wire goes to the selector switch. Confirm tap orientation with ohmmeter if unclear.

For this switch model, the lug at the bottom of the stack is connected to common when the switch is depressed. I’ll wire the tapped output to the lower lug, so the knob will be a bit higher when the pickup is in the full (higher) output mode.

Reconnect wires to selector switch according to the diagram.

Attach the new 0.047uF cap to first tone control in the same location and connections as the original. It is a good idea to use a small piece of heatshrink tubing on the cap lead going to the lug to keep it from shorting to the grounded can. As before, use the lead to make the connection to the second tone control. Attach a wire from the ground bundle to the body of the pot, not the housing of the switch.

And the wiring is done:

Clean up any solder spatters, flux residue, check wire routing to prevent pinching, etc.
This is also a good opportunity to lightly squirt some contact cleaner into any switches or pots that aren’t being changed…

Time to button it all up again and see how it sounds…

Aside from the functional changes, I’m taking the opportunity to address a cosmetic issue. With the original bridge pickup gone for good, I got a black cover for the current bridge pickup, thinking a completely different color was better than a slight difference between “new white” and “older white”. Now, I’d like them all to be the same shade as each other and anything but "new white". I did some reading and find reports of varying success with the “coffee soak” method, and decided to give it a try.

I purchased a set of white pickup covers and figured it would be too difficult to attempt a match to the existing ones, so I’m replacing them all with what should be an age-appropriate shade of faded white. I lightly buffed the covers with fine steel wool to break the surface skin to allow the coffee to penetrate better…and perhaps not completely evenly. I let all three soak for a while and check until they get to where I think they look good against the aged pickguard.

Here they are soaking nicely:

For those of you keeping a database, I used Trader Joe’s Dark French Roast (black, no sugar). The parts sat in the cold coffee for two hours, and came out looking like this:

One New, Two Old, Three Coffee-Stained

If I get inspired, I may attempt to stain a new set of control knobs as for some reason, the volume knob is a lot darker than the tone knobs. Perhaps it’s just worn more from being used much more than the tone knobs? Some other time…

Meanwhile, completing the assembly…

Lay the pickguard in place, being careful not to pinch any wires. To quickly check for problems, install one just string, more or less in tune, to make sure the pickups are all working and the various wiring and controls do what is expected – That nugget comes courtesy of the man from the angry red planet :mrgreen:

All is well so, attach pickguard with screws, add knobs and the remaining strings and tune it up.

Here is a comparison between the ‘down’ and ‘up’ positions for the push-push switch:

I’ve spent enough time adjusting pickup heights to know how thick a nickel is, so I set the new pickup more or less where it should be…and await the real test of the project…

The tapped output is a fine match for the stock pickups…clear tones with that bit of sparkle I was missing. The full output is certainly louder, but not nearly as hot as the SSL-3 (or SDS-1) and without the loss of high-end. It’s just enough to make a statement, without changing the tone too much…but not a substitute for an overdrive FX or a quick twirl of the Gain knob.

What I didn’t expect was how much the tone control would change with the new cap. Over the years, I’ve read the discussions over values…usually 0.022 vs. 0.047, and what roll-off is better for what kinds of sounds. The comments (and the physics) support high capacitance values giving lower resonance peaks and otherwise ‘dark’ tone settings (higher corner frequencies), but my stock cap (0.05) didn’t seem overly dark last week as I worked the controls to form a reference in my mind as a comparison…but I was curious…and as mentioned earlier, I was tempted to throw in a 0.022 just to see the difference.

Now, I realize what dark really meant. Apparently, and very slowly over time, ceramic capacitors (usually Barium Titanate or similar material) lose capacitance as the crystalline structure relaxes. After 35 years, there seems to have been quite a shift which was totally unnoticed to me (think about the slowly boiling frog), but after installing the fresh capacitor the tone gets very, very dark when the control gets below about 4. I’m not ready to swap it for the 0.022 yet, it’s actually very cool in a jazzy, bluesy kind of way…but I mention this as an advisory for those with old guitars…and old tone caps…that the tones you hear now may no longer be what they were when first manufactured.

I’m very happy with the project. It looks better with matching trim and I’ve got a variety of new sounds to explore…enough typing…I’ve got some playing to do…

1975 Fender Stratocaster
2012 Taylor GA3-12
1967 Epiphone Madrid EC-30

"Make every song you sing your favorite tune."

Monday, July 9, 2012

Jay Turser JTA-Flag300 - Come Together

Come together, right now
Over me

After a few more passes with the chisel, her neck slipped smoothly into her body, and things were starting to come together.  I put a clamp on the joint to get a closer look, and was pleased at how tight the fit was where her neck heel meets her body.

Next, I placed a piezoelectric pickup and a new saddle in her bridge slot so I could check her action and neck-to-body center line alignment.  With some fishing line in place of the high and low E-strings, I saw just how little work I had left to do on the dovetail joint and took care of some of it with sandpaper.

Although the neck joint was not perfect, it was close enough to drill out the neck heel and block to receive the nut insert and bolt.  I worked on her neck heel first, and laid out work lines to locate the hole.

Lacking a drill press in the This Old Guitar workshop, I used some clamps to hold her neck flat and steady to the work surface.  After setting up firring strips to get the vertical alignment, I used two hands to guide my variable speed drill.  I worked my way up with three drill bits and a slow drill speed to keep the final hole aligned with the pilot hole, and managed to get the insert right where I wanted it to be.

With a few turns of an Allen wrench, the insert installation was complete.

Moving on to the neck block, I located and marked the spot that had to be drilled out for the matching thru-bolt.  With a long straight edge, a few more firring strips and some painters tape to hold everything in place, I was ready to drill the hole.

The hole is so close to the top of the block, it's really more of a groove that receives the bolt.

After cleaning up the edges of the groove with a file, I realized I'd have to trim the top brace just behind the neck joint to allow a 11mm socket and driver to sit properly on the nut end and be able to turn it.  That was easily done from the inside of her body with a Dremel.

Since everything is such a tight fit, I also had to trim some material off at the base of the neck as well as trim the washer that distributes the compression force into the neck block.

Before a trial fit up with a set of strings, I made a run down to my local Guitar Center for a pair of black strap buttons and a set of bridge pins.  After dinner and before going to the pool that night, I put on a fresh set of D'Addario EJ15 strings.  It was great to hear some music come out of This Old Guitar, and she sounded surprisingly loud and clear.  With that, I pulled the trigger on ordering a replacement preamp unit through eBay.  The preamp is coming from China, so it will be a few more days until I have it and can install it in her existing body cavity.  Just as well, my shed is still too hot of a place to be, thanks to the current heatwave we're experiencing here in North Carolina.  That also gives me some time to make some minor finish repairs to her neck and fretboard binding that suffered some collateral damage from my chisel, as well as to add something to the neck block that will retain the bolt from slipping within the groove.  Until then, she's sitting patiently inside the This Old Guitar shed.

Wednesday, July 4, 2012

Jay Turser JTA-Flag300 - 4th of July, Asbury Park

Sandy, the fireworks are hailin' over Little Eden tonight...

Last weekend, I started in on reshaping the neck side of the dovetail joint.  Still somewhat new to using a chisel, it was only about twenty minutes before I had a minor flesh wound and had to call it a day.  After a brief visit to an urgent care, I waited a few days for the heat to let up enough to continue working in the shed.  On the way home from work yesterday, I picked up some Kevlar work gloves and a bottle of honing lubricant to use with my chisel.

After clamping the neck down to the work surface, I used some Dremel attachments and a half round file to get some the rough work done.

Even using proper chiseling technique, I managed to add some new character marks to the bass side of the neck at the heel between the 13th and 14th fret.  I'll fill them in with some matching wood and refinish the area after I finish the repairs to the neck joint.

Happy Fourth of July 2012 from This Old Guitar!

Tuesday, June 26, 2012

Jay Turser JTA-Flag300 - Riot In Cell Block No. 9

There's a riot goin' on
Up in cell block number nine.

A few weekends ago, I turned my attention back to the neck block.  The plan was to clean out all of the plastic, epoxy, or whatever Jay Turser used in the dovetail joint.  The Dremel sanding and cutting tools I had were not up to the task, so I made a quick trip to the store for a couple of new attachments.  After a few minutes of grinding, I saw how far I needed to go to get down to the wood.

After about a half hour, I had cleaned out all I was going to take out of the neck block.  After a few more minutes with a rough flat file and some sanding, it was looking like half of a a dovetail joint again.  Time to return to the neck heel.

After cleaning out the neck block, I decided to abandon the idea of converting the dovetail joint into a simple tenon joint, and decided to try building up the heel to make the dovetail.  As it is such a shallow dovetail, it might not be able to resist the tension force of the strings wanting to rotate the neck upwards and out of the joint.  That's where the bolt comes into play.  More about that after I get the heel built up and reshaped. 

Here are some shots from the past few days along the journey of getting clever with quick-clamps and oak to rebuild the heel.  Since wood has non-isotropic properties, I was careful to orient the grain of the new pieces to be parallel to the length of the neck to provide the highest strength value in compression.

Next time, I'll start shaping the neck heel into a dovetail tail so it will fit into the endblock.

Wednesday, June 6, 2012

Harmony H1203 Sovereign - How Can You Mend a Broken Heart

I can still feel the breeze
that rustles through the trees
And misty memories of days gone by.

The answer to the question the Brothers Gibb asked in this song sure wasn't a neck reset, but that's all this old guitar needed to get her high action and intonation under control.  With the latest set of oak shims attached to the heel, and very little sanding, I placed her neck back.  The dovetail joint closed up better this time, leaving no sign of a gap at the heel cap.  With her saddle in place, I laid a straight edge across the upper frets to check the projection at the saddle, and found that it was just under a 1/16 of an inch below the top of the saddle.

I restrung her and checked that same projection with each sting I added, and noticed a little change with each string.  With all six strings on and tuned, I was very pleased to find the projection only increased to about 1/8 of an inch.  I was even more pleased to find that her action was at 1/8 inch on the bass side and 1/16th of an inch on the treble side.

She played nicely and didn't need a truss adjustment at this point.  Although her action was a bit more than I would like on the low E side, there was still plenty of height left in the saddle to allow for dropping that side down to 3/32 of an inch.  I decided to leave that for next time, after letting her acclimate to the conditioned house air for at least a day to be sure her neck joint was stable.  So, I moved on to addressing a simpler problem.

All that work resetting the neck, although great for reducing her action, left a good-sized pie shape gap between the high end of her fretboard and her already sunken front panel.  Besides the aesthetics, I was worried that gluing the end of the fretboard to the front panel would stress the fretboard and binding to the point of cracking at best, lead to problems with the 14th and 15th frets being loose, and that it would leave a very obvious gap between those two frets. 

The solution I came up with was to install a shim between the top plate and the end of the fret board.  I took measurements and found that the original bridge plate was just the right thickness for making the shim.  That also seemed an appropriate way to make use of an original part of this old guitar.  After cutting and gluing up two pieces to get the width I needed, I tapered the shim on one side with a belt sander to match the profile of the gap.

When the shim fit, I traced the outline at the fretboard.  Using a coping saw, I cut the shim down to size.

With some sanding around three edges, the shim was done for now.  I left enough wood for final sanding during reassembly, and put the shim aside before putting this old guitar back in the house.  After two nights with no change in action, I do dare to call this reset a success!  This left just enough time to play a few songs before putting her and myself to bed for the night.